diff --git a/.agents/frameworks/opencode/plugin.ts b/.agents/frameworks/opencode/plugin.ts
index 47ffd1a..d8d16d2 100644
--- a/.agents/frameworks/opencode/plugin.ts
+++ b/.agents/frameworks/opencode/plugin.ts
@@ -48,6 +48,9 @@ export const GlobalPlugin: Plugin = async ({ $, client }) => {
     'chat.message': async (input, output) => {
       logInfoData('chat.message', { input, output });
 
+      const sessionID = output.message.sessionID;
+      const messageID = output.message.id;
+
       // Session-start injection — runs exactly once per session, prepended so it
       // reads before the user-prompt-submit nudges on the first turn.
       if (!initializedSessions.has(input.sessionID)) {
@@ -57,8 +60,8 @@ export const GlobalPlugin: Plugin = async ({ $, client }) => {
         if (startContext) {
           output.parts.unshift({
             id: `prt_${crypto.randomUUID()}`,
-            sessionID: input.sessionID,
-            messageID: input.messageID ?? crypto.randomUUID(),
+            sessionID,
+            messageID,
             type: 'text',
             text: startContext,
             synthetic: true,
@@ -78,8 +81,8 @@ export const GlobalPlugin: Plugin = async ({ $, client }) => {
       if (context) {
         output.parts.push({
           id: `prt_${crypto.randomUUID()}`,
-          sessionID: input.sessionID,
-          messageID: input.messageID ?? crypto.randomUUID(),
+          sessionID,
+          messageID,
           type: 'text',
           text: context,
           synthetic: true,